The present invention relates to processes and compositions for preserving aqueous systems against the deleterious action of bacteria, fungi and algae.
It is well known that various aqueous systems containing metabolizable components, either in trace or major quantities, are normally susceptible to attack and degradation by microorganisms. Examples of such compositions are cutting oils, cosmetics such as lotions and creams, fuel oil, textile emulsions, latex emulsions and paints, starch-base adhesives, industrial cooling water, emulsion waxes, water used in pulp and paper manufacture (so-called "process" water, e.g., "white water"), and flood water used in secondary oil recovery methods.
A number of problems and limitations have recently faced those in the art who seek to provide effective antimicrobial preservatives for such aqueous systems. These problems involve concerns about worker exposure and environmental impact. Many preservatives are effective because they are toxic to the microorganisms at low concentrations, i.e. concentrations in the order of about 100 parts per million. Human exposure to such preservatives in the part per million range does not normally pose a risk that raises concern. The pure product, however, may pose an unacceptable risk to workers who may be exposed to the pure concentrated material on a daily basis and who must protect themselves from accidental inhalation or accidental exposure to the skin. In the case where the substance is a liquid, its vapor pressure may be of concern, if concentrations in the air could reach levels which could be harmful to workers. If the material is a solid or a powder the inhalation of dust becomes a concern.
One way to keep the concentration of such antimicrobial agents to an acceptable handling level is to use diluents or inert carriers. Such diluents or carriers are also desirable in order to assist in delivering the antimicrobial agents to the medium to be preserved. These diluents must, of course, meet certain criteria. They must be compatible with a particular antimicrobial agent and with the medium in which the antimicrobial agent is to be used. They shouuld not be highly flammable and should not be toxic. Very few diluents can satisfy these criteria at an acceptable price.
More recently, pressures concerning the toxicity of the diluent and its compatability with the environment have served to restrict the number of diluents that are acceptable. It is expected that even fewer diluents or carriers will be acceptable in the future.
There is a need in the industry to find a diluent or a carrier system which meets the following criteria:
(1) The diluent or carrier must be compatible with the antimicrobial agent and should not diminish or destroy the antimicrobial activity.
(2) The final product must have a flash point of greater than 120 degress Fahrenheit in order to avoid dangers due to flammability.
(3) The system must work in the medium for which it is intended.
(4) It should not be on list 1 or list 2 of the Environmental Protection Agency's "Inert Ingredients in Pesticide Products; Policy Statement". (Federal Register, volume 52, number 77, dated April 22, 1987. Lists 1 and 2 cover inert ingredients of toxicological concern and potential toxicological concern, respectively.)
(5) The system must be economically competitive, i.e., it must not be so expensive that the system cannot compete in the market place.
(6) The diluent or carrier should be odorless, or at least have a pleasant odor.